Dec 31, 2012

We are glad to inform and invite to the 11th HAM eye ball meet (Mahabs meet ) @ mahabalipuram near Chennai on 9th Feb 2013.

Mahabalipuram was a 7th century port city of the South Indian dynasty of the Pallavas around 60 km south from the city of Chennai in Tamil Nadu. The name Mamallapuram is believed to have been given after the Pallava king Narasimhavarman I, who took on the epithet Maha-malla (great wrestler), as the favourite sport of the Pallavas was wrestling. It has various historic monuments built largely between the 7th and the 9th centuries, and has been classified as a UNESCO World Heritage Site.

The meet will be held as usual on second saturday the 9th feb 2013.

All hams/amateur radio enthusiasts are welcome and have pleasant eye ball .

Wishing all the HAM's / SWL / radio lovers a wonderful 2013.....may this year bring lots of good health , prosperity and happiness to all in their personal & professional life....

SPECIAL NEW YEAR VHF NET : HAPPY NEW YEAR FROM ALL CHENNAI HAMS!!!

All HAMS / SWL's / AmateursOn behalf of Madras VHF group , would like to thank all those who checked-ininto the special VHF new year net on Chennai repeater which was a great successwith local stations as well as DX stations from India / abroad also checking inthrough Echolink . Mumbai repeater , HAM's from Hyderabad , Abu Dhabi , Delhi ,Chennai , London , England , Bangalore and several others locations across India/ abroad checked in . It was a marathon 3 hours net starting at 9:00 pm andstill on as this message is being rolled out . It could be possibly the longestVHF net heard in recent days in these parts and lot of credit to VU2DPN netcontroller for taking the effort and rendering his voice for this specialmarathon VHF net which was a very new experience for all.Totally 71+ stations checked in into the special net and offered severalsuggestions/thoughts/ideas and there was open brain storming on how to furtheractivate the hobby and attract the younger generation so that the future of thehobby is secured.Same would be compiled and shared with all to workout action plan on how some ofthose could be implemented to grow this hobby further into the future.Once again wishing all a very happy,healthy & prosperous new year 2013.Thanks and RegardsFor ChennaiHamsBlogspot Team

In most countries a license to operate airband equipment is required and the operator is tested on competency in procedures, language and the use of the phonetic alphabet.

Spectrum usage

The VHF airband uses the frequencies between 108 and 137 MHz. The lowest 10 MHz of the band, from 108–117.95 MHz, is split into 200 narrow-band channels of 50 kHz. These are reserved for navigational aids such as VORbeacons, and precision approach systems such as ILS localizers.

As of 2012, most countries divide the upper 19 MHz into 760 channels for amplitude modulation voice transmissions, on frequencies from 118–136.975 MHz, in steps of 25 kHz. In Europe, it is becoming common to further divide those channels into three (8.33 kHz channel spacing), potentially permitting 2,280 channels. Some channels between 123.100 and 135.950 are available in the US to other users such as government agencies, commercial company advisory, search and rescue, military aircraft, glider and ballooning air-to-ground, flight test and national aviation authority use. A typical transmission range of an aircraft flying at cruise altitude (35,000 ft), is about 200 miles in good weather conditions.

Other bands

Aeronautical voice communication is also conducted in other frequency bands, including satellite voice on Inmarsat and high frequency voice in the North Atlantic and remote areas. Military aircraft also use a dedicated UHF-AM band from 220.0–399.95 MHz for air-to-air and air-to-ground, including air traffic control communication. This band has a designated emergency and guard channel of 243.0 MHz.

Channel spacing for voice communication on the airband was originally 200 kHzuntil 1947, providing 70 channels from 118 to 132 MHz. Some radios of that time provided receive-only coverage below 118 MHz for a total of 90 channels. From 1947–1958 the spacing became 100 kHz; from 1954 split once again to 50 kHz and the upper limit extended to 135.95 MHz (360 channels), and then to 25 kHz in 1972 to provide 720 usable channels. On 1 January 1990 the frequencies between 136.000 and 136.975 MHz were added, resulting in 760 channels.

Increasing air traffic congestion has led to further subdivision into narrow-band 8.33 kHz channels in the ICAO European region; all aircraft flying above 19,500 feet are required to have communication equipment for this channel spacing.Outside of Europe, 8.33 kHz channels are permitted in many countries but not widely used as of 2012.

The emergency communication channel 121.5 MHz is the only channel that retains 100 kHz bandwidth.

***********Info available in public domain from Air Traffic Controller's guild http://atcguild.com/ as well as from Airports Authority of India site*********

Modulation

Aircraft communications radio operations worldwide use amplitude modulation, predominantly A3E double sideband with full carrier on VHF and UHF, and J3E single sideband with suppressed carrier on HF. Besides being simple, power-efficient and compatible with legacy equipment, AM and SSB permit stronger stations to override weaker or interfering stations, and don't suffer from the capture effect found in FM. Even if a pilot is transmitting, a control tower can "talk over" that transmission and other aircraft will hear a somewhat garbled mixture of both transmissions, rather than just one or the other. Even if both transmissions are received with identical signal strength, a heterodyne will be heard where no such indication of blockage would be evident in an FM system.

Alternative analog modulation schemes are under discussion, such as the "CLIMAX"multi-carrier system and offset carrier techniques to permit more efficient utilization of spectrum.

Unauthorised use

It is illegal to transmit on the Airband frequencies without a suitable license. Many countries' regulations also restrict communications in the airband. For instance in Canada airband communications are limited to those required for "the safety and navigation of an aircraft; the general operation of the aircraft; and the exchange of messages on behalf of the public. In addition, a person may operate radio apparatus only to transmit a non-superfluous signal or a signal containing non-profane or non-obscene radiocommunications.

While it is not an offence to listen to voice transmissions in the airband frequencies, it may be an offence to possess such equipment in certain countries. Instances of such illegal activity has been the subject of international situations between governments when tourists bring airband equipment into countries which ban the possession and use of such equipment.

Dec 24, 2012

The Madras VHF Group would like to inform that to commemorate a great 2012 which was special year for all Chennai HAM's especially having successfully hosted the HAMFEST2012 after a gap of almost a decade , there would be a special VHF net conducted to welcome the new year 2013 at midnight 23:59 hrs 31st Dec 2012 / 00:00 hrs 1st Jan 2013. It would be on the regular 145.775(-600) repeater which

will also have an echo link node for remote stations across India/globe to join in.

Frequency: 145.775 (-600) / Echo link Node also would be available.

Everyone are requested to checkin and make this a successful new year special VHF net. Wishing all HAM's / SWL's /radio lovers merry christmas and advance wishes for a happy and prosperous new year. Long live the HAM Radio , longer live this passionate hobby.

Wishing all radio lovers a Merry Christmas and wishing that this special with family & friends brings a lot of joy and happiness in your life. Let HAM as a hobby continue to excite and unite people across the world for years ahead..................................

Dec 20, 2012

Update 27 November 2012: A radio enthusiast from Castlederg in County Tyrone has
been praised for saving the lives hundreds of airline passengers, from his
shed. Benny Young was turning the dial on his radio when he picked up a Mayday call
from a United Airlines flight from Dublin to Boston. Mr Young said he heard the mayday call just before moved to another
frequency. He then relayed information between the pilot and ground control at the
airport.

"I heard two people talking about Hurricane Sandy and that's what made me
stay on the Pacific frequency and I heard the mayday call," Mr Young said. "I ended up talking to the pilot for about 17 minutes and I got the man
operating the emergency net to come up to my frequency. "He could hear me, but he couldn't hear the pilot because of a problem with
the transponders on the ground which had been taken out by the storm.

"We were able to get the plane diverted because the winds were measured at 95
miles an hour at Boston."

Mr Young also helped another plane over the United States on the same
night. "The other plane automatically scanned the frequencies and must have found
us. "I didn't have the time to strike up a conversation this time. "There was great excitement at the time, it was great. "I felt good after it anyway."

Day of the hamfest at Chennai also progressed well with some good technical sessions as well as awards giving ceremony of various contests conducted last year. The valedictory function was also befitting such grant event for HAMS across India. We are sure we all look forward to another eyeball opportuniyt like this whih will next year at Gwalior.

The core team of organisers who were the backbone of the grand memorable event. Offcourse many many more behind the scenes and would call them the shadow warriors. It was a great team work and show of camaraderie by all Chennai HAMS in organising, participating and making the event a memorable one for all those you attended from all over India & abroad.

Some words on Video from VU2GMN(Gopal Madhvan) , ARSI President & Chairman IARU R3 about this HAMFEST

Video Presentation by VU2GMN

A Video tour of the flea market / HAM Bazaar which was a big attraction and crowd puller......

Technical session in progress about Solar Panels/cells as a viable alternative and clean power source for future.